a long time ago I purchased a set of different sized templates that you can cut with the small rotary cutter;
don't remember where I purchased them or from whom, sorry. I use them a lot for yo yo's.
I have also used old CD's, cups, saucers, plates or made my own with cardboard boxes and freezer paper
glued on top with the size they are...and used the small cutter on them and it works.